CDL Pre-Trip Inspection 2 — Questions and Answers
Question 1: What is the minimum tread depth required for front tires on a commercial vehicle?
- 2/32 of an inch
- 4/32 of an inch (Correct answer)
- 6/32 of an inch
- 8/32 of an inch
Correct answer: 4/32 of an inch
Front tires must have a minimum tread depth of 4/32 of an inch, while drive and trailer tires require a minimum of 2/32 of an inch.
Question 2: Which components must be checked when inspecting the air brake system during a pre-trip inspection?
- Only verify the brake pedal reaches the floor
- Brake lines, connections, chambers, slack adjusters, and brake pads or linings (Correct answer)
- Only check the parking brake lever
- Brakes only require inspection every 10,000 miles at a service center
Correct answer: Brake lines, connections, chambers, slack adjusters, and brake pads or linings
A thorough brake inspection covers all components including air lines, connections, brake chambers, slack adjusters, and pad or lining thickness and condition.
Question 3: What is the correct method to verify tire inflation pressure during a pre-trip inspection?
- Kick each tire to determine if it sounds solid
- Use a tire pressure gauge to check that each tire meets the manufacturer's recommended pressure (Correct answer)
- Visually inspect tires to determine if they appear flat
- Air pressure only needs to be checked at monthly service intervals
Correct answer: Use a tire pressure gauge to check that each tire meets the manufacturer's recommended pressure
A calibrated tire pressure gauge must be used to verify that each tire is inflated to the correct pressure; visual inspection cannot accurately detect underinflation.
Question 4: What should you look for when inspecting wheel rims during a pre-trip inspection?
- Only verify that the rims are the correct color
- Cracks, damaged areas, and that all lug nuts are present and tightened (Correct answer)
- Only check for rim roundness visually
- Rims only need inspection following a tire blowout
Correct answer: Cracks, damaged areas, and that all lug nuts are present and tightened
Rims must be inspected for cracks, physical damage, and proper lug nut installation to prevent catastrophic wheel separation while driving.
Question 5: What must be verified when checking headlights during a pre-trip inspection?
- Only that the high beams function
- Both low and high beams work, and lights are clean and properly aimed (Correct answer)
- Only that the lights turn on when the switch is activated
- Headlights only require inspection before nighttime trips
Correct answer: Both low and high beams work, and lights are clean and properly aimed
Both low and high beams must function, and lights should be clean and properly aimed to provide adequate illumination without creating a hazard for oncoming drivers.
Question 6: Why is checking wiper blades included in a pre-trip inspection?
- To ensure they produce the correct squeak sound
- To verify they clear the windshield effectively and are not damaged or worn (Correct answer)
- Wipers only require inspection before winter driving season
- Only the washer fluid level needs checking, not the blades
Correct answer: To verify they clear the windshield effectively and are not damaged or worn
Wiper blades must be in good condition and operate effectively to maintain adequate visibility in rain or adverse weather, which is critical for safe driving.
Question 7: When inspecting the fifth-wheel coupling on a tractor-trailer, what must be verified?
- Only that the fifth wheel plate is present on the tractor
- That the fifth wheel is properly mounted, lubricated, and the locking jaw is fully closed around the kingpin (Correct answer)
- Only check that the kingpin is visible
- The coupling system only needs inspection at a certified repair facility
Correct answer: That the fifth wheel is properly mounted, lubricated, and the locking jaw is fully closed around the kingpin
The fifth wheel must be securely mounted, properly lubricated, and the locking jaw must fully engage the kingpin to prevent trailer separation while driving.
CDL Pre-Trip Inspection 2
What is the minimum tread depth required for front tires on a commercial vehicle?